This invention relates to gas cooled nuclear reactors and is concerned more particularly with the construction of a coolant filter for the removal from the coolant gas of certain fission products.
The filter of the present invention is for the purpose of removing certain fission products, in particular cesium 137 from the coolant gas. As will be apparent from the following description, it will more generally serve as a filter for those radio-active species of molecular or atomic size which are absorbed by graphite at a high temperature. These include, in addition to cesium 137, strontium 90 and silver 110m.
Cesium metal release is dependent on the coolant channel surface temperature in the reactor core. The problem of cesium release therefore arises particularly with high temperature reactors. Removal of cesium from the coolant gases enables a designer to use a higher temperature and/or, provided the cesium is removed before the coolant is passed through energy extracting means to reduce the gamma exposure rate in the energy extracting means. The term "energy extracting means" used herein includes a heat exchanger and/or a turbine.